Zeolitic materials are known to have utility as sorbents and to have catalytic properties for various types of hydrocarbon conversion reactions. Certain zeolitic materials are ordered, porous crystalline materials having a definite crystalline structure as determined by X-ray diffraction, within which there are a large number of smaller cavities which may be interconnected by a number of still smaller channels or pores. These cavities and pores are uniform in size within a specific zeolitic material. Since the dimensions of these pores are such as to accept for sorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as “molecular sieves” and are utilized in a variety of ways to take advantage of these properties.
Such molecular sieves, both natural and synthetic, include a wide variety of positive ion-containing crystalline silicates and substituted silicates, in which the silicon is partially or completely replaced by other tetravalent elements. These silicates can be described as a rigid three-dimensional framework of SiO4 tetrahedra and optionally tetrahedra of a trivalent element oxide, e.g., AlO4 and/or BO4, in which the tetrahedra are cross-linked by the sharing of oxygen atoms whereby the local ratio of the total trivalent element and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing the trivalent element is balanced by the inclusion in the crystal of a cation, for example, an alkali metal or an alkaline earth metal cation. This can be expressed wherein the ratio of the trivalent element, e.g., aluminum, to the number of various cations, such as Ca/2, Sr/2, Na, K or Li, is equal to unity. One type of cation may be exchanged either entirely or partially with another type of cation utilizing ion exchange techniques in a conventional manner. By means of such cation exchange, it has been possible to vary the properties of a given silicate by suitable selection of the cation.
Molecular sieves that find application in catalysis include any of the naturally occurring or synthetic crystalline molecular sieves. Examples of these molecular sieves include large pore zeolites, intermediate pore size zeolites, and small pore zeolites. These zeolites and their isotypes are described in “Atlas of Zeolite Framework Types”, eds. Ch. Baerlocher, L. B. McCusker, D. H. Olson, Elsevier, Sixth Revised Edition, 2007, which is hereby incorporated by reference. A large pore zeolite generally has a pore size of at least 7 Å and includes LTL, VFI, MAZ, FAU, OFF, *BEA, and MOR framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of large pore zeolites include mazzite, offretite, zeolite L, VPI-5, zeolite Y, zeolite X, omega, and beta. An intermediate pore size zeolite generally has a pore size from about 5 Å to less than 7 Å and includes, for example, MFI, MEL, EUO, MTT, MFS, AEL, AFO, HEU, FER, MWW, and TON framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of intermediate pore size zeolites include ZSM-5, ZSM-11, ZSM-22, MCM-22, silicalite-1, and silicalite-2. A small pore size zeolite has a pore size from about 3 Å to less than 5 Å and includes, for example, CHA, ERI, KFI, LEV, SOD, and LTA framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of small pore zeolites include ZK-4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, chabazite, zeolite T, and ALPO-17.
Many zeolites are synthesized in the presence of an organic structure directing agent, such as an organic nitrogen compound. For example, ZSM-5 may be synthesized in the presence of tetrapropylammonium cations and zeolite MCM-22 may be synthesized in the presence of hexamethyleneimine. It is also known to synthesize zeolites and related molecular sieves in the presence of diquaternary directing agents. For example, U.S. Published Patent Application No. 2010/0178241 discloses the synthesis of EU-1 in the presence of hexamethonium cations.
According to the present invention, a new zeolite structure, designated EMM-28 and having a unique X-ray diffraction pattern, has now been synthesized using as an organic structure directing agent a novel diquat with N-methylpyrrolidinium groups connected to a phenyl ring by a linear polymethylene group of the formula (CH2)3 at the 1,3-positions (meta) or at the 1,4-positions (para).